In this paper, the propulsion performance of a bio-inspired underwater robot with a pair of ray-supported undulating pectoral fins is numerically investigated with a fully coupled fluid–structure interaction model. In this model, the flexible fin rays are represented by nonlinear Euler–Bernoulli beams while the surrounding flow is simulated via solving the Navier–Stokes equations. Kinematically, each pectoral fin is activated independently via individually distributed time-varying forces along each fin ray, which imitate effects of tendons that can actively curve the fin rays. We find that the propulsion performance of the bio-inspired robot is closely associated with the phase difference between the leading edge ray and the trailing edge ray of the pectoral fin. The results show that with a symmetrical kinematics, the highest thrust is created when the phase difference is 90 degree while the point maximizing the propulsion efficiency varies with the motion frequency. It is also found that there is a minimum frequency of generating net thrust for a specific parameter setup, which rises as the increase of phase difference. Compared with the symmetrical kinematics, the non-symmetrical kinematics generates more complicated hydrodynamic forces and moments which may be beneficial for the turning maneuver.

在本文中，通过完全耦合的流固耦合模型，对带有一对射线支撑起伏的胸鳍的生物启发式水下机器人的推进性能进行了数值研究。在该模型中，柔性鳍片射线由非线性的Euler–Bernoulli光束表示，而周围水流通过求解Navier–Stokes方程进行模拟。在运动学上，每个胸鳍通过沿着每个鳍射线的单独分布的时变力被独立地激活，这模仿了可以主动弯曲鳍射线的肌腱的作用。我们发现，仿生机器人的推进性能与胸鳍的前缘射线和后缘射线之间的相位差密切相关。结果表明，采用对称运动学，当相位差为90度时，将产生最大推力，而使推进效率最大化的点将随运动频率而变化。还发现对于特定的参数设置，存在产生净推力的最小频率，该频率随着相位差的增加而增加。与对称运动学相比，非对称运动学产生更复杂的流体动力和力矩，这可能有利于转弯机动。